Abstract: To address the efficiency bottlenecks arising from complex path planning and frequent tool changes in the machining of multi-diameter hole groups on commercial vehicle longitudinal beams, this study develops a hole-group machining path planning model that minimizes the combined idle travel time and tool change time. An improved sparrow search algorithm (ISSA) is proposed to solve the model. For the first time, tool change time corresponding to different hole diameters is explicitly incorporated as a key constraint into the optimization objective, fully accounting for the strong coupling between idle travel and tool change operations. This makes the model particularly suitable for large-scale, multi-diameter practical machining scenarios. Building on the standard Sparrow search framework, the ISSA integrates a nearest-neighbor heuristic initialization strategy to improve initial solution quality, introduces swap and inversion mutation operators to enhance global exploration, embeds periodic 2-opt local search to strengthen local exploitation, and adopts a stagnation-detection-based adaptive parameter adjustment strategy to dynamically balance exploration and exploitation. These enhancements effectively prevent premature convergence and significantly improve the algorithm’s robustness in high-dimensional discrete optimization problems. Validation using a real large-scale multi-diameter hole group (853 holes, 11 diameters) from a commercial vehicle longitudinal beam shows that the ISSA reduces idle travel time to 1654.55 s, lowers tool changes to 34, and improves overall machining efficiency by 29.55% compared with the original scheme, outperforming four other state-of-the-art optimization algorithms. The proposed method effectively shortens total machining time while maintaining path continuity, providing a reliable and practical approach for the synergistic optimization of idle travel and tool change operations in coaxial sleeve drilling.